Except for some American Express Cards (AMEX), which have 4-digit CVV codes, most CVV numbers are three digits.
At Octalas payment gateway, we accept not only VISA, Mastercard, JCB, Discover, but also American Express cards. As a result, your CVV code can be either 3 or 4 digits.
However long your CVV code might be, as long as you use a safe and secure payment gateway for your online transactions, you will be protected against virtual fraud. For example at Octalas, we have PCI DSS, 3D Secure Transaction, and Tokenization to keep you safe from internet thieves.